The present invention relates to image to film transfer. More particularly, the present invention relates to techniques and apparatus for efficient recording of images to film media.
Throughout the years, movie makers have often tried to tell stories involving make-believe creatures, far away places, and fantastic things. To do so, they have often relied on animation techniques to bring the make-believe to “life.” Two of the major paths in animation have traditionally included, drawing-based animation techniques and stop motion animation techniques.
Drawing-based animation techniques were refined in the twentieth century, by movie makers such as Walt Disney and used in movies such as “Snow White and the Seven Dwarfs” (1937) and “Fantasia” (1940). This animation technique typically required artists to hand-draw (or paint) animated images onto a transparent media or cels. After painting, each cel would then be captured or recorded onto film as one or more frames in a movie.
Stop motion-based animation techniques typically required the construction of miniature sets, props, and characters. The filmmakers would construct the sets, add props, and position the miniature characters in a pose. After the animator was happy with how everything was arranged, one or more frames of film would be taken of that specific arrangement. Stop motion animation techniques were developed by movie makers such as Willis O'Brien for movies such as “King Kong” (1933). Subsequently, these techniques were refined by animators such as Ray Harryhausen for movies including “Mighty Joe Young” (1948) and Clash Of The Titans (1981).
With the wide-spread availability of computers in the later part of the twentieth century, animators began to rely upon computers to assist in the animation process. This included using computers to facilitate drawing-based animation, for example, by painting images, by generating in-between images (“tweening”), and the like. This also included using computers to augment stop motion animation techniques. For example, physical models could be represented by virtual models in computer memory, and manipulated.
One of the pioneering companies in the computer aided animation (CA) industry was Pixar Incorporated. Pixar developed both computing platforms specially designed for CA, and animation software now known as RenderMan®. By moving to CA, Pixar was faced with additional challenges. One such challenge was how to accurately and effectively transfer CA images onto film.
As one means of recording an image on film, light is selectively introduced to the film in different areas over time, such that the effect of the combined exposures is a composite image. In one known arrangement, a laser beam is focused upon a frame of film. The laser beam is utilized to record a single pixel of an image onto the film. The laser beam is selectively directed at different areas of the frame of film in scan line sequential fashion to generate the composite image. In such an arrangement, beams of red, green and blue light are directed at the frame of film so that a color image is recorded by the film. The process of directing the laser beam at the film must be done with utmost precision or else the resultant image will suffer from visible defects.
In addition, in order for the image to have high resolution, the number of individual pixels or spots on the film which are individually exposed must be very large. The number of individually exposed pixels or spots on a frame of film may be 4000×4000 or more. Thus, in order to expose thousands of frames for a motion picture presentation, the spots are exposed at very high speed, with very high precision spot placement accuracy.
It is known to use a galvanometer to control a reflective surface which is used to deflect a light beam. In such an arrangement, a galvanometer is connected to a mirror and moves the mirror, such as in an oscillating motion. In the case of a laser film recorder, the mirror may be used to deflect the laser beam which exposes the film.
When recording a frame of film, the individual pixels or areas which are exposed by the laser beam are arranged in a Cartesian coordinate system. Pixels are arranged in rows (parallel to an “x”-axis) and columns (parallel to a “y”-axis). In order to record each pixel, the laser beam and/or film must be moved in both the “x” and “y” directions.
In prior arrangements, the laser beam is directed over the film in the “x” direction using a mirror controlled galvanometer. The film is then moved in the “y” direction with respect to the beam. Such arrangements have numerous drawbacks which are well known, including complex film drives and controls.
In order to avoid the shortcomings of systems in which the film is moved, some systems have been devised in which a mirror-controlled galvanometer is used to direct the laser beam in one dimension, and then the entire galvanometer is mounted to a rotary head unit for moving the entire device to direct the beam in the other dimension. Such a system is disclosed in U.S. Pat. No. 5,831,757 having the same assignee as herein.
This system constitutes an improvement over prior systems. Still, the rate at which the beams may be scanned over the film using this system was limited due to limitations in controlling the movement of the entire device in the required precise manner. When producing a film having thousands of frames, it is desirable to be able to scan the film as quickly as possible.
In light of the above, Pixar invented a proprietary laser film recording system named Pixarvision™ with solved many of these problems. One specific innovation was the use of two substantially independent galvanometer controlled mirrors to direct the laser beams onto film media in a highly controlled scanning fashion. Previously, laser film recording could take up to 50 seconds per frame, however with Pixar's advances in this technology, this time was reduced to about 5 seconds per frame. Further details regarding specific embodiments may be found in U.S. Pat. No. 6,628,442 assigned to Pixar, the assignee of the present patent application.
In the movie industry, two of the more conventional widescreen formats for theater screens have horizontal to vertical aspect ratios include CinemaScope (Panavision) (e.g. 2.39:1, 2.40:1, 2.35:1) and widescreen 1.85:1 (e.g. approximately 16×9). In contrast, conventional film stock, such as 35 mm film have large active regions that can support a variety of aspect ratios including approximately 1.2:1 (e.g. 1.18:1). Conventionally, for film projected at CinemaScope aspect ratios, the images are intentionally distorted and recorded in compressed (or expanded) form onto the film media. Looking at the film media, the distorted images appear as horizontally squeezed (or vertically stretched), or “anamorphic” images. In the theater, the anamorphic images are projected through and horizontally stretched (or vertically compressed) by an anamorphic lens. As a result, the image on the theater screen appears at the correct aspect ratio. In contrast, for film having a projected aspect ratio of 1.85:1, the images are recorded onto the film media (stock) with little intentional distortion. Because these images are recorded as non-anamorphic images, no anamorphic lens is required for playback.
Despite these advances, the inventors of the present invention believe that further advances could be achieved in image to film transfer.